1. Field of Invention
The present invention relates to a method for producing a Group III nitride compound semiconductor device. Particularly, it relates to a method for producing such a semiconductor device in which a leakage current is suppressed.
2. Description of the Related Art
A Group III nitride compound semiconductor device has semiconductor layers laminated on a substrate such as sapphire. Because sapphire has electrically insulating characteristic, it is impossible to provide any electrode on the substrate. Therefore, electrodes for semiconductor layers are provided on a surface side of the device. As the semiconductor layers, an n-type layer, an active layer and a p-type layer are laminated successively when viewed from the substrate side. As a result, the n-type layer is buried in the laminate. Therefore, the semiconductor layers are etched to reveal a portion of the n-type layer so that an n-electrode can be connected to the reveal portion of the n-type layer.
On the other hand, the p-type layer of Group III nitride compound semiconductor is doped with a p-type impurity. A technique of irradiating the p-type layer with an electron beam to make resistance of the p-type layer low is known.
The present inventor has repeatedly made an examination of a Group III nitride compound semiconductor device of the type having an n-electrode and a p-electrode formed on a surface side of the device and exhibiting reduction in resistance of a p-type layer due to electron beam irradiation. As a result, the inventor has found that there is fear that a leakage current may flow in between the n-electrode and the p-electrode.
Therefore, an object of the invention is to suppress the leakage current.